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Whats the difference of OTN VS SDH ?

otn vs sdh


OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy) are both technologies used in telecommunications networks for high-speed data transmission. But they were developed at different times and to solve different technical challenges. The following are the main differences and comparisons between OTN and SDH:

1. Basic concepts otn vs sdh:

    – SDH: Developed in the 1980s and early 1990s to replace PDH (Layered Digital Hierarchy). Its main purpose is to achieve interoperability between devices from different manufacturers and to provide a unified transmission structure for telephony and data services.

    – OTN: is a more modern technology designed to transparently transmit and provide various services in larger capacity optical networks, including SONET/SDH, Ethernet, Fiber Channel, etc.

2. Transmission rate:

    – SDH: Supports rates from 155.52 Mbps (STM-1) to 10 Gbps (STM-64).

    – OTN: Designed to transmit larger data volumes, supporting rates from 10G, 40G to 100G and above.

3. Transparency:

    – SDH: Mainly for TDM (Time Division Multiplexing) services, not completely transparent.

    – OTN: Provides completely transparent transmission for various data formats.

4. Scalability:

    – SDH: Although scalable, it is limited by technology and architecture.

    – OTN: has better scalability and can easily support higher data rates and new applications.

5. Monitoring and fault detection:

    – SDH: Provides end-to-end monitoring and fault detection.

    – OTN: Not only provides end-to-end monitoring, but also introduces more fault detection and diagnostic tools, such as forward error correction (FEC).

6. Flexibility:

    – SDH: Mainly focused on time division multiplexing services.

    – OTN: designed as a multi-service, multi-format optical network with greater flexibility.

7. Life cycle otn vs sdh:

    – SDH: With the emergence of OTN and other modern technologies, SDH technology is gradually being phased out.

    – OTN: regarded as the cornerstone of future optical transmission networks, combined with DWDM technology, it provides a reliable framework for future networks.

In summary, while SDH provided tremendous value to telecom networks in its era, OTN is seen as a more advanced, flexible, and future-proof technology.

What are the advantages and disadvantages of OTN VS SDH in long distance transmission?

In long-distance transmission, OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy) have their own advantages and disadvantages:

OTN (Optical Transport Network)

  advantage :

1. High-capacity transmission: OTN supports transmission rates up to 100Gbps or even higher, suitable for current and future large-capacity communication needs.

2. Transparent transmission: OTN can transparently transmit data of various protocols, including but not limited to SDH/SONET, Ethernet, Fiber Channel, etc.

3. Enhanced fault monitoring: By using forward error correction (FEC) and other monitoring tools, OTN can detect and correct errors more quickly and accurately.

4. Better scalability: With the combination of DWDM technology, OTN is able to support multiple wavelengths on the same optical fiber, thereby providing greater overall transmission capacity.

  shortcoming :

1. Cost otn vs sdh : Although prices are declining over time, the initial equipment cost of OTN is likely to be higher compared to SDH.

2. Complexity: Due to its advanced nature, OTN may require more advanced skills and knowledge to configure and manage.

SDH (Synchronized Digital Hierarchy)

  advantage :

1. Mature and stable: SDH has existed for decades, and its technology and practices have been very mature.

2. Global interoperability: SDH is an international standard and therefore has good interoperability around the world.

3. Good monitoring capabilities: SDH provides end-to-end fault and performance monitoring.

  shortcoming :

1. Capacity limitation: The maximum transmission rate of SDH is relatively low, which may not be enough to meet the needs of modern communications compared with OTN.

2. Not flexible enough: SDH is mainly designed for TDM (Time Division Multiplexing) and is not as flexible as OTN when processing multiple protocol data.

3. Difficult to expand: As data needs grow, expanding an SDH network can be more complex and expensive.

When choosing the right technology for long-distance transmission, there are trade-offs based on specific transmission needs, budget, and future expansion plans.

What are the advantages and disadvantages of OTN VS SDH in large-capacity transmission?

In large-capacity transmission, the comparison between OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy) is as follows:

### OTN (Optical Transport Network)

  advantage :

1. Ultra-high-speed transmission: OTN can support transmission rates from 10Gbps, 40Gbps to 100Gbps or even higher.

2. Multi-protocol capability: Able to transparently transmit various data protocols, such as Ethernet, SDH/SONET, Fiber Channel, etc.

3. Support large-capacity DWDM: Combined with dense wavelength division multiplexing (DWDM) technology, OTN can provide Tbps-level overall transmission capacity on a single optical fiber.

4. Stronger signal quality and integrity: Forward Error Correction (FEC) technology and other enhanced monitoring features ensure signal quality is maintained over long distances and high-capacity transmissions.

  shortcoming :

1. Equipment cost: The cost of high-speed OTN equipment may be higher than traditional SDH equipment.

2. Management complexity: Higher technical knowledge is required to manage and maintain OTN equipment and networks.

### SDH (Synchronized Digital Hierarchy)

  advantage :

1. Mature technology: SDH has been used for long-distance transmission for decades and is considered reliable and stable.

2. Standardization and interoperability: Due to its international standards, SDH equipment has good interoperability and is easy to integrate.

3. End-to-end monitoring: SDH’s management system provides good end-to-end fault and performance monitoring.

  shortcoming :

1. Rate upper limit: Although the SDH rate has increased from 155Mbps to 10Gbps, its upper limit is still relatively low compared with OTN.

2. Not flexible enough: SDH is designed for TDM and is not as flexible as OTN in transmitting various protocol data.

To sum up, for large-capacity transmission, OTN provides higher rates and greater overall capacity, while SDH is more suitable for traditional and more mature network environments.

OTN VS SDH,what to consider if customizing optical transmission solutions ?

When customizing optical transmission solutions, you need to make full use of the respective advantages of OTN and SDH. Here are some suggestions:

### 1. Consider the network environment and needs


– If your network is mainly based on an existing SDH environment and does not anticipate significant expansion or upgrade in the future, then it is appropriate to continue using SDH.

– For applications that require end-to-end monitoring, fixed latency, and existing standardized interoperability, SDH is more suitable.


– OTN is the first choice for new or upgraded networks that require high speed, large capacity or handle multiple data types.

– If you anticipate demand growth or protocol changes in the future, OTN provides better scalability and flexibility.

### 2. Cost considerations


– Lower initial investment (especially if SDH equipment already exists).

– If the network is not large or does not require high speeds, SDH may be a more cost-effective option.


– Although the initial investment may be higher, for large-scale, high-speed applications, the cost per bit of transmission will be lower in the long run.

– Able to provide higher overall transmission capacity on a single fiber, reducing fiber core requirements and costs.

### 3. Future expansion of otn vs sdh


– Although it can be expanded, major upgrades may be required after reaching a certain capacity.

– If not many changes are expected in the future, then SDH is a stable choice.


– Excellent scalability, easy to add more channels or upgrade to higher rates.

– Better prepared for future growth and change.

### 4. Network management and maintenance


– Utilizing existing management systems and experience makes it easier to maintain SDH networks.


– Provides a more powerful fault detection and recovery mechanism, which is valuable for applications requiring high availability.

### Summarize

When customizing an optical transmission solution, you should first evaluate current and future network needs, budget, and available resources. Combine the advantages of OTN and SDH and choose the most suitable technology or hybrid technology solution to meet specific transmission needs.

OTN VS SDH, why is OTN better than SDH?

OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy) are both technologies used for optical network transmission, but they were developed in different technical backgrounds and eras. Here are some reasons why OTN may be considered superior to SDH in certain application scenarios:

1. Higher bandwidth and speed: With the rapid growth of data traffic, OTN is able to support higher bandwidth and speed, such as 100G, 200G and even 400G, while SDH technology is limited in this regard.

2. Transparent transmission: OTN provides a more “transparent” transmission that can easily transmit various customer signals, such as Ethernet, Fiber Channel, SONET/SDH, etc., without the need for signal conversion.

3. Enhanced fault management: OTN has enhanced fault detection and location capabilities, such as forward error correction (FEC) and optical layer monitoring functions, which help quickly detect and recover network problems.

4. Better scalability: OTN has excellent scalability and can easily support new rates and protocols, which makes it more suitable for responding to rapidly changing network needs.

5. Reduced Complexity: As network speeds increase, so does the complexity of SDH. OTN provides a simplified method to handle high-rate data, making network management simpler.

6. Better digital encapsulation: OTN’s digital encapsulation provides unified transmission for various services, which not only optimizes bandwidth utilization but also ensures high-quality service transmission.

7. Support flexible multi-layer network: OTN supports flexible multi-layer network design, allowing it to be seamlessly integrated with other technologies such as WDM (Wavelength Division Multiplexing) technology.

Although OTN shows advantages in many aspects, this does not mean that SDH has no value. In some scenarios, especially those where a large amount of infrastructure has already been established, it may be more appropriate to continue using SDH. However, for new networks that require high bandwidth and high flexibility, OTN is often the better choice.

OTN VS SDH, what is the difference in transmission rate?

OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy) are two main transmission technologies used in optical communication networks. There are some significant differences between the two when it comes to transfer rates:


– The original intention of SDH was to provide a unified standard for digital transmission, mainly used for telephone communications. SDH provides a range of standardized rates.

– The basic rate is STM-1, which is equal to 155.52 Mbps.

– Higher speed grades such as STM-4 (622.08 Mbps), STM-16 (2.5 Gbps), STM-64 (10 Gbps), etc. Although rates can theoretically continue to increase, SDH typically does not exceed 10 Gbps for technical and economic reasons.


– OTN is designed to support wavelength division multiplexing (WDM) technology and other data flows including SDH. It is also designed to support higher data rates.

– The basic rate unit of OTN is OTU (Optical channel Transport Unit). The original OTN standard is OTU1, which is equivalent to STM-64 and operates at 2.66 Gbps.

– OTN rates subsequently experienced several increases, such as OTU2 (10.71 Gbps), OTU3 (43.018 Gbps) and OTU4 (112 Gbps). This enables OTN to support 100G and is expected to support 400G and higher transmission rates in the future.


1. SDH has limited growth in transmission rates, typically up to 10 Gbps.

2. OTN is designed to support higher transmission rates. It has already achieved 100 Gbps transmission and is expected to support higher rates in the future.

Therefore, OTN offers greater flexibility and scalability from a transmission rate perspective, especially given the higher bandwidth requirements of modern networks.

OTN VS SDH, what are the differences in frame structure?

There are some significant differences in the frame structure between OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy). The following are the main frame structure characteristics of both technologies:

  SDH frame structure:

1. STM-N frame: SDH uses a frame structure called STM-N, the most common of which is STM-1 frame. The STM-1 frame size is 270 x 9 bytes.

2. Segmentation: The frame is divided into rows and columns, where the first row is used for the beat header (Section Overhead) and the row cover header (AU – Administrative Unit pointer).

3. Pointers: SDH uses a pointer mechanism to solve the problem of clock desynchronization.

4. Payload and coverage: SDH frames contain payload (such as voice and data) and coverage (such as beat header).

  OTN frame structure:

1. OTUk frame: OTN uses a frame structure called OTUk, where k can be 1, 2, 3, 4, etc. For example, the OTU2 frame size is 4080 x 16 bytes.

2. Forward Error Correction (FEC): OTN includes a FEC (Forward Error Correction) area to improve the robustness of transmission against the increase in Bit Error Rate (BER).

3. Bus interface: Unlike SDH, OTN is designed to be more transparent and capable of transmitting many different loads, such as Ethernet, SONET/SDH or native optical signals.

4. Extended coverage: OTN frames provide rich coverage areas, including global coverage (GCC), multi-frame coverage (MFC) and rotation indicator coverage (TCM).


– SDH’s frame structure is more focused on the synchronous transmission of telephone sounds, so its frame structure is designed to handle and synchronize different time sources.

– The design focus of OTN is to provide a transparent, high-capacity optical transmission network that supports multiple load types. Its frame structure includes an emphasis on error correction and provides greater flexibility for transmission at high speeds and multiple service types.

The frame structures of these two technologies reflect their respective design goals and application domain needs.

OTN VS SDH, the difference between multiplexing modes?

There are some significant differences in the multiplexing modes between OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy). These differences mainly stem from the design goals and application scenarios of the two technologies.

  SDH multiplexing mode:

1. Synchronous multiplexing: The main feature of SDH is that it uses synchronous multiplexing technology. In this multiplexing method, low-rate signals are first mapped into fixed-capacity containers, and then these containers can be multiplexed by high-rate signals.

2. Containers and virtual containers: SDH reuse is achieved through the use of containers (C) and virtual containers (VC). These containers are designed to accommodate fixed bit rate payloads, such as voice signals or data signals.

3. Fixed mapping: SDH provides predefined mappings for the various services it supports. For example, an E1 signal can be mapped into a VC-12 virtual container.

  OTN multiplexing mode:

1. Digital multiplexing: OTN uses digital multiplexing, where various client signals are first mapped onto standard OTN shelves and can then be multiplexed onto higher-rate OTN shelves.

2. Transparent multiplexing: One of the main advantages of OTN is its transparent multiplexing capability. This means that OTN can seamlessly carry many different types of customer signals, such as SDH/SONET, Ethernet, optical signals, and more.

3. Flexible mapping: Compared with SDH, OTN provides more flexible mapping options. Client signals can be mapped to ODU (Optical Data Unit), and the size and rate of the ODU can be selected as needed.


– SDH’s multiplexing patterns are fixed and predefined, providing optimization for synchronous transmission and specific types of services. This is central to its design, allowing it to serve the telephone network efficiently.

– OTN’s multiplexing is more flexible and transparent, enabling it to support a variety of different signal types and applications. This multiplexing model allows OTN to meet a wider range of market needs, from core transport networks to inter-data center interconnects.

The reuse patterns of these two technologies reflect their design philosophies and application areas.

OTN VS SDH, the difference between reuse mapping structures

OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy) are two technologies widely used in the field of optical transmission. They have their own unique reuse mapping structure. Here are some of the main differences between them:

1. Basic structure:

    – SDH: The basic transmission unit of SDH is STM (Synchronous Transport Module), such as STM-1, STM-4, STM-16, etc. STM-1 is equal to 155.52 Mbps, which is the minimum transmission rate of SDH. Low-speed services are first mapped to containers (Container, C), and then these containers are reused into virtual containers (Virtual Container, VC), and then further reused to higher-order STM levels.

    – OTN: The basic unit of OTN is ODU (Optical Data Unit), such as ODU0, ODU1, ODU2, etc. ODU0, ODU1, ODU2, etc. respectively correspond to different transmission rates and have a multi-level structure, allowing them to transparently multiplex various client signals.

2. Mapping structure:

    – SDH: The mapping structure of SDH is relatively fixed, usually including containers, virtual containers, payloads and transport modules. Specific services (such as E1, E3, E4 or STM-1, etc.) are first mapped into fixed-size containers, and then these containers are further mapped into VCs.

    – OTN: OTN provides a more flexible mapping structure, allowing multiple signal types, such as SDH/SONET, Ethernet, Fiber Channel, etc., to be mapped to ODUs. This mapping provides better transparency and flexibility, especially for large and irregularly sized loads.

3. Reusability:

    – SDH: SDH mainly focuses on time multiplexing. The low-level service signal is first time-multiplexed into a high-level signal, and then further multiplexed to a higher STM level.

    – OTN: OTN focuses on wavelength multiplexing and digital multiplexing. OTN allows multiple signals to be transmitted simultaneously on the same optical fiber, each signal using a different wavelength, thus achieving wavelength division multiplexing (WDM).

4. Scalability and adaptability:

    – SDH: SDH is designed for telephone switched networks and is well optimized for fixed-size services (such as telephone signals). However, for large-capacity or irregular-sized services, SDH’s mapping and multiplexing structure may be less flexible.

    – OTN: OTN is designed to handle a variety of different signal types and rates, making it more adaptable to changing network needs.

In general, SDH and OTN provide different multiplexing mapping structures based on their design goals and application fields respectively. As network needs evolve and change, OTN is becoming more widely used in many modern optical transport applications due to its flexibility and adaptability.

OTN VS SDH, the difference in overhead levels

In OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy) technologies, overhead is used for signal management and monitoring. This overhead information can be used to tell the transceiver device about the status and quality of the transmitted signal. The following are the main differences between OTN and SDH at the overhead level:

1. Overhead size:

    – SDH: The overhead structure of SDH is relatively simple. The overhead of the STM-1 frame is mainly located at the beginning of the frame and is divided into segment overhead (SOH) and line overhead (AU-LOH). Among them, SOH is further divided into regeneration section overhead (RSOH) and multiplex section overhead (MSOH).

    – OTN: The overhead structure of OTN is relatively complex. It includes ODU overhead, OTU overhead and light overhead (GCC).

2. Overhead function:

    – SDH:

      – RSOH: includes information such as bit error performance, remote fault indication, remote error indication, etc.

      – MSOH: includes timestamp, S1 byte (synchronization status), remote error indication, remote fault indication, error performance and other information.

    – OTN:

      – ODU overhead: including general communication channel, error performance, remote error indication, remote fault indication, clock correction and other information.

      – OTU overhead: Provides frame synchronization, forward error correction (FEC) and related monitoring and management functions.

      – GCC: Allows operators for network management and communications.

3. Overhead scalability and flexibility:

    – SDH: SDH overhead design is relatively fixed and is designed for traditional telephone signals.

    – OTN: OTN overhead provides more flexibility, especially for high-capacity and heterogeneous networks. For example, OTN’s Tandem Connection Monitoring (TCM) field allows for multiple levels of monitoring.

4. Forward Error Correction (FEC):

    – SDH: Traditional SDH does not have FEC capabilities.

    – OTN: OTN provides FEC in its OTU overhead, which is a very important feature, especially on long-distance and sub-quality links, because it can improve the fault tolerance and overall performance of the transmission.

In general, OTN provides a more detailed, flexible and feature-rich overhead structure to meet the needs of modern optical networks. These overheads allow for deeper signal monitoring, more advanced error correction, and broader network management capabilities. As an early technology, SDH has a simpler overhead structure and is mainly oriented to early communication needs.

OTN VS SDH, the difference between TTI mode

TTI (Trail Trace Identifier) ​​is an identifier used to monitor and identify a connection or communication path. In both SDH and OTN, TTI plays an important role, but they are different in implementation and use.

1. SDH’s TTI:

    – In SDH, TTI is usually called J0 byte (in regeneration section overhead) and J1 byte (in high-order VC path overhead).

    – J0 is used to monitor connections at the segment level, while J1 is used for monitoring at the VC-3 or VC-4 path level.

    – These bytes contain a contiguous 16-byte ASCII string indicating the source of the connection, as well as some other identifying information.

    – When the path switches or fails, the TTI change can be detected by the remote device.

2. OTN’s TTI:

    – In OTN, TTI comes in many forms, depending on the layer. For example, there is TTI for ODUk and TTI for OTUk.

    – The TTI length of OTN is 64 bytes, which is longer than the TTI of SDH.

    – These TTIs are designed to provide more connection identification information, as well as deeper monitoring of the connection.

    – OTN’s TTI also changes when a path failure or switchover occurs, allowing the remote device to quickly detect the problem.

  Main differences:

    – Length: The TTI length of SDH is 16 bytes, while the TTI length of OTN is 64 bytes.

    – Usage location: In SDH, TTI is mainly used at the segment and VC path levels, while in OTN, TTI can be used at multiple levels.

    – Flexibility and information volume: Due to the increased length, OTN’s TTI can provide more connection identification and monitoring information.

In short, TTI is a key monitoring tool in both SDH and OTN, but there are obvious differences in implementation and use. As network needs evolve, OTN’s TTI provides more advanced and flexible monitoring capabilities.

OTN VS SDH, the difference in BIP processing

BIP (Bit Interleaved Parity) is a mechanism for detecting bit errors and is commonly used in communication systems. In both SDH and OTN, BIP is used, but the implementation details and application methods are different.

1. BIP in SDH:

    – What is used in SDH is BIP-8 (for segment layer) and BIP-24 (for multiplexed segments).

    – BIP-8 is mainly used to monitor the regeneration section (REGEN) of STM-1 level. The first 9 lines of each STM-1 frame (except the J0 byte) are used to calculate BIP-8.

    – BIP-24 is used to monitor multiplex segments (MS) at STM-N level. This BIP is calculated for the entire STM-N frame (except RSOH).

    – Bit errors can be detected at the end of a segment by comparing the received and sent BIP values.

2. BIP in OTN:

    – OTN uses BIP-8, but it is slightly different from the implementation in SDH.

– In OTN, BIP-8 is used to monitor the OTU (Optical Transport Unit) level. Calculate the data range of BIP-8

The range varies depending on the specific OTUk level (such as OTU2, OTU3, etc.).

    – There are other BIPs in OTN, such as BIP-8 at the Tandem Connection Monitoring (TCM) layer, which are used to monitor sub-paths at the ODU level.

    – Similar to SDH, bit errors can be detected at the end of a specific layer by comparing the received and sent BIP values.

 Main differences:

 – Location of use: BIP in SDH is mainly used in the regeneration section and multiplexing section, while BIP in OTN is used at the OTU and ODU levels.

 – Calculation scope: SDH’s BIP usually calculates a part of the entire STM frame, while OTN’s BIP calculation scope depends on the specific OTUk level.

   – Other BIPs: OTN provides more BIP options, such as TCM layer BIP, for more refined error detection.

In short, although both SDH and OTN use BIP for error detection, there are differences in implementation details and usage methods. OTN provides more flexible and sophisticated error detection tools to meet the needs of modern optical communication networks.

OTN VS SDH, performance handling difference :

OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy) are optical network transmission technologies designed to meet high-speed communication requirements. Both have their own performance handling mechanisms for monitoring, managing and optimizing the network. The following are the main differences in performance processing between OTN and SDH:

1. Performance monitoring indicators:

  – SDH:

* SDH’s performance monitoring is mainly based on its BIP (Bit Interleaved Parity) error detection mechanism.

* Commonly used performance indicators include bit error rate (BER), dropped pointer events, sliding window events, etc.

*SDH also uses the G.826 and M.2100 series of recommended standards for performance evaluation.


 * OTN performance monitoring takes into account more factors, such as optical signal attenuation, dispersion, polarization mode dispersion (PMD), etc.

 * OTN uses Forward Error Correction (FEC) to detect and correct errors, which also provides data for performance evaluation.

 * The performance indicators of OTN include bit error rate (BER), number of error blocks (Block Errors), backward error rate, etc.

2. Performance management:

– SDH:

* SDH network mainly performs performance management through network management system (NMS).

* NMS can collect performance data of network equipment in real time, analyze it, and provide necessary alarms and notifications to operation and maintenance personnel.


* OTN networks also use NMS for performance management, but it also includes more intelligent diagnostic tools, such as optical power monitoring, spectrum analysis, etc.

* OTN’s performance management system can predict potential problems, such as microscopic damage in optical fibers, allowing maintenance to be carried out in advance.

3. Performance optimization:

    – SDH:

      *The performance optimization of SDH mainly relies on its fixed transmission hierarchy and structure.

      * Typically, performance optimization includes adding redundancy, optimizing signal paths, using higher quality optical fiber and equipment, etc.


      * OTN allows more flexible signal processing, such as wavelength routing, dynamic wavelength allocation, etc., which provides more possibilities for performance optimization.

      * OTN can better adapt to changing network conditions, such as traffic demand, signal attenuation, etc.

In summary, both OTN and SDH provide complete performance processing mechanisms, but OTN has greater flexibility and higher accuracy in performance monitoring, management and optimization. This makes OTN more suitable for modern high-speed, large-capacity optical communication networks.

OTN VS SDH, the difference between static load pointers :

In OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy), static load pointers and dynamic load pointers are important mechanisms for adjusting timing. The following are the main differences between OTN and SDH in static load pointers:

1. Definition and purpose:

    – SDH:

      * In SDH, pointers are the mechanism used to resolve the problem of small differences between clocks.

      * When asynchronous signals need to be aligned, SDH uses static load pointers and dynamic load pointers.

      * The static load pointer does not involve actual changes in the pointer value, but provides a fixed reference.

    – OTN:

      * OTN is not designed to replace SDH, but it provides similar functions to deal with timing issues.

      * OTN’s timing processing is more complex and does not directly use static load pointers similar to those in SDH. It uses the overhead bytes of the OTUk frame to make corresponding timing adjustments.

2. Operation:

    – SDH:

      * When an SDH device receives a data rate slightly faster than its internal clock, the deadload pointer “moves” to align the data flow.

      * If the received data rate is too fast, causing the buffer to overflow, the dynamic load pointer will be adjusted.

    – OTN:

      * OTN timing adjustment is not implemented through pointer movement, but through other mechanisms, such as overhead bytes.

3. Application scenarios otn vs sdh:

    – SDH:

      * SDH’s static load pointer and dynamic load pointer are mainly used in STM-N frames to deal with timing issues in the container (VC).

    – OTN:

      * OTN deals with the timing issues of optical communication networks, not electrical communication networks. The method it uses is more complex and adapted to higher speed and large-capacity transmission.

Generally speaking, SDH and OTN adopt different methods and technologies when dealing with timing and alignment issues. SDH uses mechanisms such as static load pointers and dynamic load pointers, while OTN has its own unique processing method.

OTN VS SDH, the difference between maintaining signals :

OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy) both have their own maintenance signal systems to ensure the health and stability of network operations. Here are the main differences between the two in maintaining signals:

1. Definition and purpose:

    – SDH:

      *The maintenance signals in SDH are called OAM (Operations, Maintenance and Management) information. These signals are used for fault management, configuration management, performance management and security management.

      * In SDH, there are specific overhead bytes (such as BIP, BERR, etc.) used for fault monitoring and performance monitoring.

    – OTN:

      * OTN also has its OAM function, but its implementation and details are slightly different from SDH.

      * OTN defines dedicated overhead for each layer (such as OTU, ODU and OPU layers) for fault monitoring, performance monitoring and other maintenance tasks.

2. Working principle:

    – SDH:

      *BIP (Bit Interleaved Parity) in SDH is used for error monitoring.

      * SDH uses maintenance signals such as MS-AIS and LP-AIS to identify faults.

    – OTN:

      * There are also BIP-like functions in OTN, but they may be called BIP-8, BIP-32, etc., depending on which layer it is at.

      * OTN uses ODU-AIS, OPU-AIS and other signals to identify faults.

3. Signal propagation and processing:

    – SDH:

      * When an error or fault is detected, the SDH device will send the corresponding AIS signal.

      * RDI (Remote Defect Indication) signal is used to notify the remote device of a fault.

    – OTN:

      * In OTN, when a problem is detected, an AIS signal is also generated.

      * OTN also includes other specific maintenance signals and identifiers, such as Backward Defect Indication (BDI).

4. Application and scalability:

    – SDH:

      * SDH’s OAM function is mainly aimed at its specific transmission level and rate.

    – OTN:

      * The OAM function of OTN is designed to be more flexible and scalable, adaptable to OTN networks of various speeds and levels.

In short, although both OTN and SDH have maintenance signal systems for network health monitoring and fault management, they are different in implementation details, applications, and working principles. OTN, as a newer technology, provides more flexibility and scalability.

OTN VS SDH, the difference between light protection :

otn vs sdh

Both OTN (Optical Transport Network) and SDH (Synchronous Digital Hierarchy) support optical protection mechanisms to ensure the reliability and stability of communication links. Here are the main differences between the two when it comes to light protection:

1. Basic concepts:

    – SDH: SDH mainly uses mechanisms such as MSP (Multiplex Section Protection) and SNCP (Subnetwork Connection Protection) for optical protection. MSP is a 1+1 protection method, that is, sending two copies of the same signal, while SNCP uses 2-fiber BLSR (double-fiber ring automatic protection switch) or 4-fiber BLSR.

    – OTN: OTN has introduced new protection mechanisms in its structure, such as ODUk SNCP and ODUk SPRing. In addition, OTN can also support traditional WDM protection mechanisms, such as 1+1, 1:1 and M:1 protection.

2. Flexibility and efficiency:

    – SDH: In SDH, the protection methods are often relatively fixed, which may lead to a waste of bandwidth. For example, in 1+1 protection mode, the backup link does not transmit actual service traffic under normal circumstances.

    – OTN: OTN provides higher flexibility. For example, OTN’s ODUk SNCP can support 1:1 protection, allowing service traffic to be transmitted on the backup link, thereby improving bandwidth utilization.

3. Working principle:

    – SDH: When a failure of the main link is detected, the SDH protection mechanism will automatically switch to the backup link.

    – OTN: OTN’s protection switching response time is faster and can support more protection levels and options.

4. Compatibility and upgrades:

    – SDH: The protection mechanism of SDH is mainly applicable to SDH networks and may not be flexible enough for high-speed and large-capacity WDM networks.

    – OTN: Since OTN is designed with compatibility with WDM networks in mind, its protection mechanism is more suitable for modern high-speed optical networks.

5. Scalability for otn vs sdh:

    – SDH: The protection mechanism of SDH is difficult to adapt to emerging network technologies and needs, such as ultra-high speed and flexible optical routing.

    – OTN: OTN’s protection mechanism is more modular and scalable, and can more easily adapt to future technological developments and demand changes.

In general, although both OTN and SDH support optical protection mechanisms to enhance network reliability, OTN provides higher flexibility, efficiency, and scalability. With the development of optical network technology, the advantages of OTN will become more obvious in terms of protection and recovery.

If you have any questions or inquiries ,please contact HYD TECHNOLOGY team .Thanks !

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